Trailer hitch

ABSTRACT

A load equalizing hitch for trailers and the like having a spring bar assembly in which the bar is adjustable angularly in a vertical direction with respect to the ball mount of the hitch, thereby permitting an adjustment of the spring bars relative to one another and to the head to compensate for wear of the hitch parts and fatigue of the spring bars. Each of the two spring bars is adjustable independently of the other and is pivotally connected to the fixture of the assembly. After an adjustment has been made, the spring bar is locked in its adjustable position with respect to the fixture, forming a rigid operative structure.

United States Patent Weber [54] TRAILER HITCH [72] Inventor: Charles A.Weber, Elkhart, Ind.

[73] Assignee: Elkhart Welding & Boiler Works, Inc.,

Elkhart, lnd.

[22] Filed: Jan. 18, 1971 [21] Appl. No.: 107,349

[ 1 July 25,1972

Hedgepath ..280/406 A Dalton ..280/406 A 5 7 ABSTRACT A load equalizinghitch for trailers and the like having a spring har assembly in whichthe bar is adjustable angularly in a vertical direction with respect tothe ball mount of the hitch, thereby permitting an adjustment of thespring bars relative to one another and to the head to compensate forwear of the hitch parts and fatigue of the spring bars. Each of the twospring bars is adjustable independently of the other and is pivotallyconnected to the fixture of the assembly. After an adjustment has beenmade, the spring bar is locked in its adjustable position with respectto the fixture, forming a rigid operative structure.

9 Claims, 7 Drawing Figures PATENTEDJMZ m2 3.679.232

SHEET 1 0F 2 INVENTOR. CHARLES/1.5% 85/? BY 4% )"M ATTORNEYS PATENTEBJHLWZ 3.679.232

SHEET 2 OF 2 90 I l INVEVTOR.

. I30 CHA/PL 5541446551? ATTORNEYS TRAILER HITCH Mobile homes, housetrailers, and similar vehicles normally use a single pair of wheels or atandem wheel undercarriage located to the rear of the center of thevehicle. With vehicles of substantial length, this places an excessiveamount of weight on the rear end of the towing vehicle, and hence thefront end of the trailer and the rear part of the towing vehicle sag ordip, placing an undue load on the rear wheels of the towing vehicle andcausing the trailer to assume a forwardly tilted position. Various typesof devices have been used in the past to overcome this difficulty, anumber of which include a single or dual bar attached to the trailerhitch and extending rearwardly from the towing vehicle beneath or alongthe side of the forward end of the trailer frame. These bars areresilient and are usually connected to the trailer frame by a yieldablecoupling means such as a chain, which together permit some flexing tooccur between the trailer and towing vehicle at the hitch.

These prior load equalizing mechanisms have had certain inherentdifficulties which have rendered them unsatisfactory, inconvenient toinstall and maintain, and/or even dangerous under certain roadconditions or driving maneuvers, including difficulty in locating thehead of the hitch at the proper angle with respect to the towing vehicleso that the spring bars will be in proper position along the trailerframe to permit satisfactory adjustment with the spring bar lift at therear end of the bars. The hitch head or ball mount is normally welded tothe tow bar at the desired attitude, and the tow bar is secured to thetowing vehicle. If the proper angle of the ball mount is not obtainedduring the welding operation, or if undue wear occurs in the hitch orfatigue develops in' the spring bars, the spring bars cannot be adjustedto the required capacity for equalizing the load between the towed andtractive vehicles. For example, if the welder tilts the ball mount toofar forwardly, the required tension could not be obtained by the springbar lifts, or wear in the spring bar pivot means may likewise preventthe required tension of the spring bars. It is therefore one of theprincipal objects of the present invention to provide a load equalizinghitch for connecting a trailer to a towing vehicle, in which thevertical angle of the spring bars can be adjusted with respect to theball mount so that the angle at which the ball mount is attached to thetow bar is not critical, and excessive amount of wear in the spring barpivot means will not prevent proper adjustment of the spring barsthroughout the life ofthe hitch.

Another object of the invention is to provide a trailer hitch having aload equalizing mechanism therein, which gives maximum adjustability tominimize the effect of human error in installing the hitch and in thewear of the hitch parts, and which permits the hitch to be installedwith a wide tolerance range.

Still another object of the invention is to provide a relatively simple,strong and compact trailer hitch having a load equalizing mechanismtherein, which can be readily fabricated and assembled and which can beeasily installed on an automobile and trailer and thereafter readilyadjusted over a wide range of ball mount angles without the use ofspecial tools or equip ment. I

A further object is to provide a load equalizing mechanism of theaforesaid type, having a pair of readily detachable spring barspivotally connected at one end to the trailer hitch by a socketconstruction forming a part of the bars and connected at the other endto the trailer frame by a yieldable adjustable means, which can bereadily and accurately adjusted with respect to the ball mount and toone another by one or two simple operations when the hitch is installedand from time to time thereafter as wear occurs in the hitch mechanismand fatigue occurs in one or both of the spring bars.

Additional objects and advantages of the present invention will becomeapparent from the following description and accompanying drawings,wherein:

FIG. 1 is a perspective view of a load equalizing trailer hitchembodying the present invention, showing the hitch mounted on a draw barand connected to the forward frame members of a trailer;

FIG. 2 is a perspective view of the load equalizing hitch shown in FIG.I, with certain parts thereof disassembled;

FIG. 3 is a fragmentary, partial vertical cross sectional view of thepresent load equalizing hitch, taken on line 3-3 of FIG.

FIG. 4 is an enlarged bottom view of the fixture used in conjunctionwith the present load equalizing hitch;

FIG. 5 is an end view of the fixture shown in FIG. 4;

FIG. 6 is a vertical cross sectional view of the fixture shown in FIGS.4 and 5, taken on line 6--6 of FIG. 3; and

FIG. 7 is a top plan view of the fixture.

Referring more specifically to the drawings, and to FIG. I inparticular, numeral 10 designates generally a trailer having angularlypositioned frame members 12 and 14, preferably joined together at theirforward end l6 by welding. The forward end of the frame members supportsa plate 18 for a retractable parking wheel structure partially shown atnumeral 20. The load equalizing hitch is shown generally at numeral 22and is connected to a towing vehicle, such as a conventional automobile,by a draw bar 24, the bar preferably being rigidly bolted at one end tothe rear axle of the automobile and supported on the bumper at the otherend by any suitable securing means. The rearward end of draw bar 24includes a releasable attachment means 26 for the hitch. Various typesof draw or tow bars may be used in conjunction with the load equalizinghitch; however, the draw or tow bar for larger sized trailers isnormally of a type adapted to be secured to the rear axle of theautomobile. The trailerson which the present hitch can be mounted may beof various sizes and constructions, andon the majority of the largetrailers to which the present hitch is particularly applicable, theframe members are in the angular position shown. For the purpose of thepresent invention, the draw bar and trailer frame members are consideredconventional and of well known construction, and will not be describedin detail herein.

- The load equalizing hitch embodying the present invention consistsprincipally of ball mount bracket 30, spring bar assembly 32 and springbar assembly 34(The bracket is constructed of metal and is provided witha cylindrical projection 36, extending forwardly from the bracket andreceived in attachment means 26, the projection 36' being held inattachment means 26 by a transversely positioned pin38 extending throughboth the attachment means and the projection. This pin is readilyremovable from its positionin the attachment means to permit theprojection to be withdrawn therefrom when bracket 30 is being removedfrom the towing vehicle. The projection is welded rigidly to bracket 30,and the desired angular position of the ball mountbracket with respectto the vehicles is obtained by the angle of the bracket on projection 36when the two parts are welded together, or, as in some assemblies, whenthe bracket is welded directly to the draw bar.

The ball mount bracket 30 consists of an upper horizontal support plate40 and lower horizontal support members 42 and 44, the two members beingjoined rigidly to vertical support members 46 and 48, respectively, thelatter two members in turn being joined rigidly to the underside ofupper plate 40. This entire hitch bracket is preferably constructed ofcast steel with the parts thereof being joined integrally to oneanother. Upper plate 40 contains a hole for receiving a stem 52 of ball54, the ball being held rigidly in place by a suitable securing meanssuch as a pin or nut on the lower end of stem 52 beneath plate 40. Thehitch bracket 30, together with projection 36 and ball 54, forms theprincipal part of the towing vehicle part of the present hitch, and canbe used in this form V in conjunction with conventional type socketmeans on the trailer, such as that shown at numeral 60, consisting of acap 62 forming a socket for receiving ball 54 and having a latchingmechanism 64 for retaining the ball in the socket while the trailer isbeing towed by the automobile.

The hitch bracket is provided with upper bearing members 66 and 68joined rigidly at their upper ends to the underside of plate 40 and tothe upper surface of members 42 and 44,

respectively, by connecting members 70 and 72. Bearing members 66 and 68are cylindrical in shape and are somewhat smaller in diameter thanmembers 70 and 72 in order to provide the supporting shoulders 74 and 76for the spring bar fixture. The hitch is provided with lower bearingmembers 80 and 82 projecting downwardly from the underside of supportmembers 42 and 44, respectively, and being cylindrical in shape andjoined rigidly to the respective support members. The cylindricalbearing members 66 and 80 and bearing members 68 and 82 are in axialalignment and of substantially the same diameter, and are adapted tosupport one end of the spring bar assemblies 32 and 34.

The two spring bar assemblies 32 and 34 are identical in construction,each consisting of an elongated resilient steel bar 90 and fixture 92connected to the forward end of spring bar 90. Bar 90 which is connectedat the rear end to frame bracket assembly 94, may be of various crosssectional shapes in addition to that shown in the drawings, such asrectangular or round, and may be of various lengths and sizes dependingupon the intended installation. Fixture 92 includes a yoke portion 98and a socket portion 100, the yoke portion defining a U-shaped recess106 for receiving one of the upper bearing members 66 or 68. Thecurvature of U-shaped recess 106 is substantially the same as thebearing members, and the recess is smaller than members 70 and 72 sothat the lower edge 108 of yoke 98 will seat on and be supported byshoulder 74 or 76. Socket portion 100 consists of an outer wall 110spaced downwardly from yoke 98 and defining an elongated recess 112, theelongation of the recess being parallel with the spring bar and the wall114 at the forward end of the recess forming a bearing surface forengaging the forward side of lower bearing members 80 or 82.

The spring bar assembly is mounted on the hitch bracket in the mannerillustrated in FIG. 3 with the inner surface of U- shaped recess 106engaging the rear side of upper bearing member 66 or 68, and the forwardside 114 of the wall defining recess 112 engaging the forward side oflower bearing member 80 or 82. In assembling the spring bar, socketportion 100 is first slipped upwardly onto lower bearing member 80 or 82while the spring bar is tilted downwardly sufficiently to maintain theyoke and the upper bearing member in spaced relation. After the socketportion has been moved upwardly against support member 42 or 44, thespring bar is then tilted upwardly to place the yoke 98 around upperbearing member 66 or 68 with the rear surface of the latter bearingmember against the inner surface of U-shaped recess 106. In order toremove the spring bar assembly from the hitch bracket, the reverseoperation is performed.

After the spring bar assembly has been mounted on the hitch bracket inthe foregoing manner, the rear or free end thereof is attached by ayieldable frame bracket assembly 94, the one shown in FIGS. 1 and 2consisting of a chain 120 attached to the end of the spring bar by abolt and eye 122 and a U-shaped bracket 124 placed over the upper edgeof the respective frame member and having an outwardly projecting pin126 for receiving the proper link ofchain 120. The chain is held inplace on pin 126 by a cotter key 128 or the like. Preferably, bracket124 is held in place by a set screw 130 or a pin extending through thetwo arms of bracket 124 and through the frame member. A lift mechanismor bracket may be used in place of bracket 124 in order to obtain thedesired amount of tension on the bars. A suitable lift bracket isdisclosed in Design Pat. No. D 213,6l6, and it is used with chain 120.The amount of tension on the spring bars can be varied by selectingdifferent links in chain 120 for pin 126. When the proper adjustment hasbeen made, the frame members 12 and 14 and draw bar 24 are substantiallyhorizontal and parallel to one another.

Inorder to compensate for maladjustment of hitch 22 on the draw bar andfor undue wear in the moving parts of the hitch or fatigue of the springbars, an adjustment mechanism is included in fixture 92 of each springbar assembly, thus permitting each bar to be adjusted individually inaccordance with requirements. In the embodiment illustrated in thedrawings the forward end of bar is seated in a socket in the fixture.The socket is generally of a width substantially the same as thethickness of the bar 90 and of a height substantially greater near theforward end than at the opening 131 through which the bar extends. Thepart of the fixture shown at collar 132, through which the bar extends,forms, in effect, a pivot point 134 which permits the forward end of thebar to move upwardly and downwardly, with the rearward end of the barmoving upwardly and downwardly in the opposite direction in a greateramount. The desired vertical adjustment is obtained by a pair of setscrews and 142, screw 140 having a rounded end 144 which seats in arounded recess I46 in the end of the bar. The two screws are threadedinto their respective holes in the fixture and are adjusted upwardly ordownwardly when an adjustment is to be made. For example, if moretension is to be placed on the bar by the adjustment, the forward end ofthe bar, i.e., the portion projecting inwardly into socket 130 in thefixture, is adjusted upwardly by set screw 140 after set screw 142 hasbeen retracted. This results in a downward tilting of the spring barrearwardly from pivot point 134, i.e., the elongated exposed part of thebar. After an adjustment has been made by tightening screw 140, setscrew 142 is then tightened to hold the bar rigidly in place, with theupper end 144 of screw I40 seated in recess 146. After the two screwshave been adjusted to provide the proper angularity of the bar withrespect to the fixture and ball mount, the screws are locked by nuts 148and 150, respectively. The screws permit the bar to be adjusted over awide range and, after the adjustment has been made, they effectivelyretain the bar rigidly in place in the fixture so that the fixture andbar function as a unitary structure. Since the wear involving the twobars and the fatigue which may occur during the normal life of thespring bars are often not the same, the individual adjustment for thetwo bars provides maximum accuracy in obtaining the requiredequalization of spring bar tension on opposite sides of the trailerframe. Likewise, if the two spring bars should initially have adifferent strength, the two bars can be adjusted to equalize thisdifference and thereby obtain maximum equalization on opposite sides, toincrease the safety and reliability of the hitch.

After the hitch has been assembled on the towing and towed vehicles inthe manner previously described herein, and the two spring bars adjustedto provide substantially equal load transferring characteristics betweenthe towed and the towing vehicles, the hitch operates over extendedperiods of time without requiring adjusting.

While only one embodiment of the present hitch mechanism has beendescribed in detail herein, various changes may be made in the type ofadjustment mechanism between the spring bar and assembly fixture or ballmount. and the spring bar assembly can be adapted to other types andmakes of load equalizing trailer hitches.

lclaim:

1. In a load equalizing hitch having a ball mount bracket, two angularlypositioned spring bar assemblies, and frame bracket assemblies forsupporting the rear end of the spring bars: each of said spring barassemblies comprising a spring bar, a fixture for connecting said springbar to the ball mount bracket, and means for adjusting, in the verticaldirection, the angularity of the bar with respect to the ball mountbracket.

2. A spring bar assembly for a load equalizing hitch as defined in claim1 in which said fixture includes a part for receiving the end of saidbar, and pivot means on said fixture near the forward end of said bar.

3. A spring bar assembly for a load equalizing hitch as defined in claim2 in which said adjustment means includes a set screw.

4. A spring bar assembly for a load equalizing hitch as defined in claim2 in which said adjustment means includes a pair of set screws forpivoting said bar on said pivot means and for locking said bar in anadjusted position.

5. A spring bar assembly for a load equalizing hitch as defined in claim1 in which said fixture consists of a body having a socket opening tothe rear receiving one end of said bar and extending vertically aboveand below said bar, the part of said fixture defining said openingforming a pivot point for said bar means in said body for tilting thebar.

6. A spring bar assembly for a load equalizing hitch as defined in claim5 in which said adjustment means for tilting said bar includes a setscrew.

7. A spring bar assembly for a load equalizing hitch as defined in claim5 in which said adjustment means includes a pair of opposed set screwsarranged vertically to one another for adjusting the bar angularly andlocking the bar in an adjusted position. v

8. A spring bar assembly for a load equalizing hitch as defined in claim6 in which a recess isprovided in the corresponding end of said bar forreceiving the inner end of said set screw.

9. A spring bar assembly for a load equalizing hitch as defined in claim7 in which said fixture is constructed of steel and said set screws arethreaded into the body of said fixture with one set screw in the lowerportion thereof and the other set screw in the upper portion thereof.

1. In a load equalizing hitch having a ball mount bracket, two angularlypositioned spring bar assemblies, and frame bracket assemblies forsupporting the rear end of the spring bars: each of said spring barassemblies comprising a spring bar, a fixture for connecting said springbar to the ball mount bracket, and means for adjusting, in the verticaldirection, the angularity of the bar with respect to the ball mountbracket.
 2. A spring bar assembly for a load equalizing hitch as definedin claim 1 in which said fixture includes a part for receiving the endof said bar, and pivot means on said fixture near the forward end ofsaid bar.
 3. A spring bar assembly for a load equalizing hitch asdefined in claim 2 in which said adjustment means includes a set screw.4. A spring bar assembly for a load equalizing hitch as defined in claim2 in which said adjustment means includes a pair of set screws forpivoting said bar on said pivot means and for locking said bar in anadjusted position.
 5. A spring bar assembly for a load equalizing hitchas defined in claim 1 in which said fixture consists of a body having asocket opening to the rear receiving one end of said bar and extendingvertically above and below said bar, the part of said fixture definingsaid opening forming a pivot point for said bar means in said body fortilting the bar.
 6. A spring bar assembly for a load equalizing hitch asdefined in claim 5 in which said adjustment means for tilting said barincludes a set screw.
 7. A spring bar assembly for a load equalizinghitch as defined in claim 5 in which said adjustment means includes apair of opposed set screws arranged vertically to one another foradjusting the bar angularly and locking the bar in an adjusted position.8. A spring bar assembly for a load equalizing hitch as defined in claim6 in which a recess is provided in the corresponding end of said bar forreceiving the inner end of said set screw.
 9. A spring bar assembly fora load equalizing hitch as defined in claim 7 in which said fixture isconstructed of steel and said set screws are threaded into the body ofsaid fixture with one set screw in the lower portion thereof and theother set screw in the upper portion thereof.